Photographic color processes, products, and compositions



3,d7?,d@2 Patented F ab. 12, 1963 3,077,402 PHUTOGRAPHIC COLOR PRQCESSEE, PRODUCTS, AND CGMPOSHTIGNS Elkan R. Blont, Belmont, Saul G. Cohen, Lexington, Mil=- ton Green, Winthrop, and Myron S. dimon, Waltharn, Mass., assignors to Polaroid Corporation, '(Iambridge, Mass, a corporation of Delaware No Drawing. Filed Dec. 6. 1954, Ser. No. 473,458 Claims. ((31. 96-29) This invention relates to photography and more particularly to products, compositions and processes for the development of photosensitive silver halide elements.

it is one object of the present invention to provide novel processes and compositions for the development of silver halide emulsions, in which colored developing agents are used to develop a latent image.

Another object is to provide novel processes and compositions for the development of silver halide emulsions, in which the novel developing agent is capable of developing a latent image and imparting a reversed or positive colored image of said latent image to a superposed image-receiving material.

A further object is to provide novel products, processes and compositions suitable for use in preparing monochromatic and multichromatic photographic images.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the processes involving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products and compositions possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

A new group of photographic developing agents has been discovered having the formula:

wherein Z is an aryl group possessing a silver halide developing function, X and Y are aryl groups, such as phenyl, diphenyl or naphthyl. The term aryl" is intended to include both substituted and unsubstituted aryl groups. Among the suitable substituents may be mentioned hydroxyl, alkyl, sulfo, amino, alkoxy, etc. Thus, X may be derived from H acid, S acid, Chicago acid, etc. Y may be derived, for example, from benzidine, dianisidine or an amino-naphthol sulfonic acid. In addition to reducing the exposed silver halide of the latent image, these developing agents may also deposit a colored image in situ with the developed image; thus they may be referred to as dye developers, and more particularly, disazo dye developers.

The photographic processes and compositions dis-closed herein are particularly useful in the treatment of a latent image present in a photosensitive element, such as an exposed silver halide emulsion, whereby a positive dye image thereof may be imparted to another element, herein referred to as an image-carrying or image-receiving element.

U.S. Letters Patent Nos. 2,559,643 and 2,647,049 to Edwin H. Land disclose examples of such diffusion transfer reversal processes wherein the photographic negative material, such as a photographic element comprising an exposed silver halide emulsion layer containing a latent image, is processed to impart to an image-receiving element a reversed or positive dye image of said latent image by permeating into said emulsion layer a suitable liquid processing composition and bringing said emulsion layer into superposed relationship with an appropriate image-receiving layer.

In carrying out the process of this invention, a photosensitive element containing a silver halide emulsion is exposed and wetted with a liquid processing composition, for example by immersing, coating, spraying, flowing, etc., in the dark, and the photosensitive element superposed, prior to, during or after wetting, on an image-receiving element. 'In a preferred embodiment, the photosensitive element contains a layer of dye developer, and the liquid processing composition is applied to the photosensitive element in a uniform layer as the photosensitive element is brought into superposed position with an image-receiving element. The liquid processing composition permeates the emulsion to provide a solution of dye developer substantially uniformly distributed therein. As the latent image is developed, the oxidation product of the dye developer is immobilized or precipitated in situ with the developed silver, thereby providing an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition. This immobilization is apparently primarily due to a change in the solubility characteristics of the dye developer upon oxidation, and especially as regards its solubility in alkaline solutions. It may also be due, in part, to a tanning effect on the emulsion by the oxidized developing agent. At least part of this imagewise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed image-receiving element, said transfer substantially excluding silver or oxidized dye developer. The latter element receives a depthwise diffusion, from the emulsion, of unoxidized dye developer, Without appreciably disturbing the imagewise distribution thereof, to provide a reversed or positive, colored image of the negative image. The image-receiving element may contain agents adapted to mordant or otherwise fix the diffused, unoxidized dye developer. In the event that dye developers within the scope of this invention are sensitive to pH changes in the image-receiving element, the pH of that element may be adjusted .in accordance with known techniques to obtain a pH according the desired color to the diffused dye developer. Im-bibition periods of approximately one minute have been found to give good results, but this contact period may be ad justed where necessaryto compensate for variations in temperature or other conditions. The desired positive image is revealed by stripping the image-receiving element from the photosensitive element at the end of the imbibition period.

The dye developers of this invention may be utilized in the photosensitive element, for example in, on or behind the silver halide emulsion, or they may be utilized in the image-receiving element or in the liquid processing composition. In a preferred embodiment, a coating or layer of the dye developer is placed behind the silver halide emulsion, i.e., on the side of the emulsion adapted to be located most distant from the photographed subject when the emulsion is exposed and preferably also adapted to be most distant from the image-receiving element when in superposed relationship therewith. Placing the dye developer behind the emulsion layer, as in the preferred embodiment, has the advantage of providing increased contrast in the positive image, and also minimizes any light-filtering action by the colored dye developer. In this preferred embodiment, the layer of dye developer may be applied by using a coating solution containing about 0.5 to 8%, by Weight, of the dye developer. Similar concentrations may be used if the dye developer is utilized as a component of the liquid processing composition.

The liquid processing composition above referred to comprises at least an aqueous solution of an alkaline compound, for example diethylamine, sodium hydroxide or sodium carbonate, and may contain the dye developer.

smmoe In some instances, it may contain a minor amount of a conventional developing agent. If the liquid processing composition is to be applied to the emulsion by being spread thereon, preferably in a relatively thin, uniform layer, it may also include a viscosity-increasing compound constituting film-forming material of the type which, when spread over a water-absorbent base, will form a relatively firm and relatively stable film. A preferred filmforrning material is a high molecular weight polymer such as a polymeric, Water-soluble ether inert to an alkali solution, as, for example, a polyacrylate. Other filmforming materials or thickening agents whose ability to increase viscosity is substantially unaffected when left in solution for a long period of time may also be used.

The novel disazo dye developers of this invention may be prepared by diazo coupling. For example, where Y is derived from benzidine or dianisidine, a tetrazonium derivative thereof may be condensed with the above defined X and Z compounds, or the condensation may be stepwise, using a diazonium derivative and condensing one end with X or Y, followed by diazotization and coupling at the other end. In certain instances, the groups X and Z may be diazotized and separately coupled into Y. Where, as in the preferred embodiment, the developing function of Z is supplied by hydroxyl groups, it is preferable to protect one or more of the hydroxyl groups to avoid undesired side reactions, as by esterification. The protective group is removed by hydrolysis after completion of the reaction and prior to photographic use.

As examples of disazo dye developers included Within the scope of this invention, mention may be made of the following:

2- [p-( l-hydroxy-3 ,6-disulfo-S-amino-Z-naphthylazo) -3,3

dimethoxybiphenyleneazo] -hydro quinone.

2- p-( l-hydroxy-S ,7 -disulfo-8-amino-2-naphthylazo) -3 ,3

dimethoxybiphenyleneazo] -hydroquinone.

2- [p- (2-hydroxy-3-carboxyl-naphthylazo) -3,3'-dimethoxybiphenyleneazo] -hydroquinone.

2- [7- (m-nitrophenylazo) -l-hydroxy-5-sulfo-8-amino-2- naphthylazo] -hydroquinone.

2- [7- (m-nitrophenylazo -1-hydroxy-3,6-disulfo-8-amino- 2-naphthylazo] -hydroquinone.

2-[p-( 1-hydroxy-3,6-disulfo-8-amino-2-naphthylazo)-3,6-

dimethoxyphenylazo] -hydroquinone.

2- [p-( 1-hydroxy-3,6-disulfo-8-amino-2-naphthylazo) phenylaminophenylazo] -hydroquinone.

2- [p-( 1-hydroxy-5-sulfo-8-amino-2-naphthylazo -3,3 '-dimethoxy-biphenyleneazo 1 -hydro quinone.

2-[p-(1-hydroxy-4-sulfo-2-naphthylazo)-3,3 -dimethoxy- 'biphenyleneazo] -hydroquinone.

Z has been defined herein and in the claims as an aryl group possessing a silver halide developing function. Although the Z portions of the disazo dye developers given above as illustrations have been derived from hydroquinone type compounds, i.e., the silver halide developing function comprises a pair of hydroxyl groups substituted, with respect to each other, in the para positions on a benzene nucleus, it is not intended to so limit Z. Other substituents may be used to supply this function, such as amino, alkylamino and/ or hydroxyl groups substituted in the ortho or para positions, with respect to each other, on a benzene nucleus. Other substituents which do not destroy the silver halide developing function may also be present, such as alkyl, halogen, etc. Reference is made to The Theory of the Photographic Process, C. E. K. Mees (1st ed., 1942), The Macmillan Co., New York, N.Y., p. 342 et seq., for a discussion of the substituents which impart a silver halide developing function to an aryl nucleus.

Example 1 o-Dianisidine (2.44 g.) is suspended in 5 cc. of concentrated hydrochloric acid and 10 cc. water. This suspension is cooled to 0 C. and diazotized by the addition of 1.4 g. of sodium nitrite in 5 cc. of water. Stirring is continued for five minutes after addition of the sodium nitrite is completed. The reaction mixture is filtered and the precipitate washed with 15 cc. of water. The filtrates are combined and added to a solution of hydroquinone sodium monosulfate. The latter is made by boiling a solution of 3.73 g. of the pyridine salt of hydroquinone monobenzoate monosulfate in 25 cc. of 25% sodium carbonate for five minutes, diluting with 50 cc. of water and cooling to 5 C. The mixture of tetrazotized odianisidine and hydroquinone sodium monosulfate is stirred for an hour at 5 C. A solution of 2.55 g. of H acid (3,6-disulfo-8-amino-l-naphthol) in 25 cc. of water and 10 cc. of 25% sodium carbonate is then added and stirring continued at 5 C. for another hour. The reaction mixture is then heated briefly on a steam bath and the disazo product salted out with sodium chloride. The mixture is filtered and the precipitate dissolved in 50 cc. of water. Concentrated hydrochloric acid (10 cc.) is then added and the mixture brought to a boil. The mixture is then cooled, filtered and the precipitate washed with a little cold water. The product is a blue dye developer, 2- [p-1-hydroxy-3,6-disulfo-S-amino-Z-naphthylazo) 3,3'-dimethoxy biphenyleneazo]-hydroquinone, which is soluble in aqueous alkali but only slightly soluble in water.

An example of a photographic use of the disazo dye developers of this invention, and set forth by way of illustration only is:

Example 2 Acetone 8O Methanol 20 Ethyl Cellosolve 1 After this coating has dried, a silver iodo-bromide emulsion is applied. An image-receiving element is prepared by coating a baryta base with a 6% aqueous polyvinyl alcohol solution. The photosensitive element is exposed and a liquid processing composition comprising:

Water cc Sodium hydroxide g 2.0 Metol g 0.2 Sodium polyacrylate g 1.5

applied thereto as it is brought into superposed relationship with the image-receiving element. After an imbibition period of approximately one minute, the image-receiving element is separated and contains a navy blue, positive dye image of the photographed subject.

It will be noted that the liquid processing composition may, and in the above example does, contain a minor amount of a conventional developer, such as Metol. The amount of this conventional developer used is 'insuflicient to give appreciable negative density by itself, and merely serves to accelerate and possibly initiate the action of the dye developer.

In the practice of this invention, the film-forming material employed in the liquid processing composition and the carrier medium employed to apply the disazo dye developer coating are preferably materials to which the disazo dye developers exhibit a low sub-stantivity. Examples of such materials include sodium polyacrylate and gum arabic. The surface of the image-receiving element to which the disazo dye developer dilfuses preferably comprises a material to which the disazo dye developer exhibits a high substantivity, e.g., polyvinyl alcohol, sodium carboxymethyl cellulose, regenerated cellulose or a hydroxyethyl cellulose. Where it is desired to form the positive image in the layer of film-forming material which adheres to,and remains with, the image-receiving element, one may use soluble materials of this type in the'liquid processing composition.

The novel compounds of this invention are also useful as dyes for textile fibres as, for example, nylon fibres. The dye developers of this invention may be used also in conventional photographic processes, such as tray or tank development of conventional photosensitive films, plates or papers to obtain black-and-white, monochromatic or toned prints or negatives. By way of example, a developer composition suitable for such use may comprise an aqueous solution of approximately 1-2% of the dye developer, 1% sodium hydroxide, 2% sodium sulfite and 0105 potassium bromide. After development is completed, any unreacted dye developer is washed out of the photosensitive element, preferably with an alkaline washing medium or other medium in which the unreacted dye developer is soluble. The expression toned is used to designate photographic images wherein the silver is retained with the precipitated dye, whereas monochromatic'is intended to designate dye images freeof silver. I It should be noted that the dye developers of this invention are self-suflicient toprovide the desired color image and do not depend upon coupling reactions to produce the desired color. They thus provide ,a; complete departure from conventional photographic color processes in which the color is producedby a couplingreaction between a color former or coupler and the oxidized developing agent, as well as scalled auto-coupling processes in which color is obtained by a reaction of the oxidized developing agent with unoxidized developingagent, I It 'will be apparent that, by appropriate selection of the image-receiving element from among suitable known opaque and transparent materials, it is possible to obtain either a colored positive reflection print or a colored positive transparency. Likewise, the inventive concepts herein set forth are adaptable for multicolor work by the use of special photographic materials, for example film materials of the type containing two or more photosensitized ele ments associated with an appropriate number of imagereceiving elements and adapted to be treated with one or more liquid processing compositions, appropriate dye developers suitable to impart the desired subtractive colors being incorporated in the photosensitized elements or in the liquid processing compositions. Examples of such photographic materials are disclosed in the previously mentioned U.S. Patent No. 2,647,049 to Edwin H. Land.

The inventive concepts herein set forth are also adaptable for the formation of colored images in accordance with the photographic products and processes described and claimed in the copending application of Howard G. Rogers, Serial No. 415,073, filed March 9, 1954, now abandoned and replaced by application Serial No. 748,421, filed July 14, 1958, and issued as Patent No, 2,983,606 on May 9, 1961, and also those set forth in the copending application of Edwin H. Land, Serial No. 448,441, filed August 9, 1954, now U.S. Patent No. 2,968,554 issued January 17, 1961.

In the preceding portions of the specificationthe expression color has been frequently used. This expression is intended to include the use of a plurality of colors to obtain black, as well as the use of a single black dye developer.

Since certain changes may be made in the above products, compositions and processes without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A photographic developer composition comprising an aqueous alkaline solution containing 2-[p-(1-hydroxy- 3,6-disulfo-8-amino-2-naphthylazo) 3,3 dimethoxy-biphenyleneazo] -hydroquinone.

2. A photographic developer composition comprising an aqueous alkaline solution containing Z-[p-(I-hydroxy- 5,7-disulfo-8-amino-2-naphthylazo) 3,3 dimethoxy-biphenyle neazo] -hydroquinone.

3. A photographic developer composition comprising an aqueous alkaline solution containing 2-[7-(mwnitrophenylazo)-1-hydroxy-5-sulfo-8-amino-2 naphthylazoJ- hydroquinone.

4. A process of developing a latent image present in an exposed silver halide emulsion which comprises developing said emulsion with an aqueous alkaline solution of a compound of the formula:

wherein Z is a hydroquinonyl group; Y is a bivalent aromatic radical which comprises an aromatic nucleus se lected from the group consisting of benzene, biphenyl and naphthalene nuclei, a nitrogen atom of each of said -N=N- groups being attached to a different carbon atom of said nucleus; and X is a monovalent aromatic radical which comprises an aromatic nucleus selected from the group consisting of benzene, biphenyl and naphthalene nuclei, a nitrogen atom of said N=N- group being attached to a carbon atom of said nucleus; for a time sufiicient to develop said latent image to silver.

5. The process of developing a latent image present in an exposed silver halide emulsion which comprises developing said emulsion with an aqueous alkaline solution containing 2-[p-(1-hydroxy 3,6 disulfo-d-amino-Z-naphthylazo -3,3 '-dimethoxy biphenyleneazo] -hydroquinone.

6. The process of developing a latent image present in an exposed silver halide emulsion which comprises devel oping said emulsion with an aqueous alkaline solution containing 2 [p-(1-hydroxy-5,7-disulfo-8-amino-2-naphthylazo)-3,3'-dimethoxy biphenyleneazo]-hydroquinone.

7. The process of developing a latent image present in an exposed silver halide emulsion which comprises developing said emulsion with an aqueous alkaline solution containing 2- [7- (m-nitrophenylazo 1-hydroxy-5-sulfo-8- amino-Z-naphthylazo]-hydroquinone.

8. A photographic product comprising a silver halide emulsion and a compound of the formula:

wherein Z is a hydroquinonyl group; Y is a bivalent aromatic radical which comprises an aromatic nucleus selected from the group consisting of benzene, biphenyl and naphthalene nuclei, a nitrogen atom of each of said N=N- groups being attached to a different carbon atom of said nucleus; and X is a monov'alent aromatic radical which comprises an aromatic nucleus selected from the group consisting of benzene, biphenyl and naphthalene nuclei, a nitrogen atom of said N=N group being attached to a carbon atom of said nucleus.

9. A photographic product comprising .a silver halide emulsion and 2-[p-(1l1ydroxy 3,6 disulfo-8-amino-2- naphthylazo) 3,3 dimethoxy-biphenyleneazo]-hydroquinone.

10. A photographic product comprising a silver halide emulsion and 2-[p-(1-hydroxy 5,7 disulfo-8-amino-2- naphthylazo) 3,3 dimethoxy-biphenyleneazo]-hydroquinone.

11. A photographic product comprising a silver halide emulsion and 2-[7-(m-nitrophenylazo)-1-hydroxy-5-sulfo- 8-amino-2-naph-thylazo]-hydroquinone.

12. In a process of forming photographic images in color, the steps which comprise developing a latent image contained in an exposed silver halide emulsion with an aqueous alkaline solution of a disazo dye developer of the formula:

wherein Z is a hydroquinonyl group; Y is a bivalent aromatic radical which comprises an aromatic nucleus selected from the group consisting of benzene, biphenyl and naphthalene nuclei, a nitrogen atom of each of said --N=N-- groups being attached to a different carbon atom of said nucleus; and X is a monovalent aromatic radical which comprises an aromatic nucleus selected from the group consisting of benzene, biphenyl and naphthalene nuclei, a nitrogen atom of said N=N groupbeing attached to a carbon atom of said nucleus; to thereby provide in said emulsion a predetermined distribution of unoxidized disazo dye developer, and trans fcrring at least part of said distribution of unoxidized disazo dye developer, by imbibition, from said emulsion to an image-receiving element in superposed relationship with said emulsion to impart to said image-receiving element a reversed, positive dye image of the developed image.

13. In a process of forming photographic images in color, the steps which comprise developing a latent image contained in an exposed silver halide emulsion 'with an aqueous alkaline solution of the disazo dye developer Z-[p-(I-hydroxy 3,6 disulfo-8-amino-2-naphthylazo)- 3,3-dirnethoxy-biphenyleneazo] -hydroquinone to thereby provide in said emulsion a predetermined distribution of unoxidized disazo dye developer, and transferring at least part of said distribution of unoxidized disazo dye developer, by imbibition, from said emulsion to an imagereceiving element in superposed relationship with said emulsion to impart to said image-receiving element a reversed, positive dye image of the developed image.

14. In a process of forming photographic images in color, the steps which comprise developing a latent image contained in an exposed silver halide emulsion-with an aqueous alkaline solution of the disazo dye developer Z-[p-(I-hydroxy 5,7 disuIto-8-amino-2-naphthylazo)- 3,3-dimethoxy-biphenyleneazo]-hyroquinone to thereby provide in said emulsion a predetermined distribution of unoxidized disazo dye developer, and transferring .at least part of said distribution of unoxidized disazo dye developer, by imbibition, from said emulsion to an imagereceiving element in superposed relationship with said emulsion to impart to said image-receiving element a reversed, positive dye image of the developed image.

15. In a process of forming photographic images in color, the steps which comprise developing a latent image contained in an exposed silver halide emulsion with an aqueous alkaline solution of the disazo dye developer 2-[7-(m-nitrophenylazo) 1 hydroxy-5-sulfo-8-arnino-2- naphthylazo]-hydroquinone to thereby provide in said emulsion a predetermined distribution of unoxidized disazo dye developer, and transferring at least part of said distribution of unoxidized disazo dye developer, by im bibitio-n, from said emulsion to an image-receiving element in superposed relationship with said emulsion .to impart to said image-receiving element areversed, posh tive dye image of the developed image.

References Cited in the fite of this patent UNITED STATES PATENTS 2,088,907 Holzach et al Aug. 3, 1937 2,146,040 Wilmanns et al Feb. 7, 1939 2,214,446 Albers et al Sept. 10, 1940 2,277,262 Stein et al. Mar. 24, 1942 2,521,908- Glass et al. Sept. '12, 1950 2,698,244 Land Dec. 28, 1954 FOREIGN PATENTS 541,073 Great Britain Nov. 12, 1941 OTHER REFERENCES Mees: The Theory of the Photographic Process, Macmillan, New York, 1954, pages 546, 551, and 553. 

12. IN A PROCESS OF FROMING PHOTOGRAPHIC IMAGES IN COLOR, THE STEPS WHICH COMPRISE DEVELOPING A LATENT IMAGE CONTAINED IN AN EXPOSED SILVER HALIDE EMULSION WITH AN AQUEOUS ALKALINE SOLUTION OF A DIAZO DYE DEVELOPER OF THE FORMULA: 